Percentage Calculator
Work out a percentage of a number, what percent one number is of another, and percentage increase or decrease.
Last reviewed July 1, 2026
Percentages come up everywhere — discounts, tips, tax, grades, interest, statistics — and it's easy to blank on which number to divide by. This calculator handles the three questions people ask most, each with a plain-English answer and the working shown.
Pick the type of calculation, enter your two numbers, and get the result instantly. No formulas to remember.
The three common percentage questions
‘What is X% of Y?’ multiplies: for example 20% of 150 is 0.20 × 150 = 30. Use it for discounts, tips, and tax.
‘X is what percent of Y?’ divides then multiplies by 100: 30 out of 150 is (30 ÷ 150) × 100 = 20%. Use it for scores, shares, and proportions.
‘Percentage increase or decrease’ compares an old and new value: (new − old) ÷ old × 100. A rise from 150 to 180 is a 20% increase; a fall to 120 is a 20% decrease.
Frequently asked questions
▶How do I calculate a percentage of a number?
Multiply the number by the percentage divided by 100. For 15% of 80: 80 × (15 ÷ 100) = 12. The 'percent of a number' mode above does this for you.
▶How do I work out percentage increase?
Subtract the original value from the new value, divide by the original value, and multiply by 100. From 200 to 250 is (250 − 200) ÷ 200 × 100 = 25%.
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Open calculator →Disclaimer: Percentage Calculator results are estimates for general information and education only, and are not financial, tax, legal or medical advice. Verify important decisions with a qualified professional.